Inspired Python

Tower Defense Game: Getting Started

2022-03-29T12:42:14.843402+00:00

Tower Defense Game: Getting Started

Python package management is not the easiest thing to wrap your head around. Nevertheless, it’s important that we capture the requirements our game has, properly, and commit them to a Python package.

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Tower Defense Game: Menus, Sound & Text

2022-03-29T12:42:14.854856+00:00

Tower Defense Game: Menus, Sound & Text

We’re nearly done with the game. It’s time to put some effort into the UI so we can save and load maps we make and play them. For that we need a little menu system. Then there’s the matter of retrofitting sound into the game also.

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Tower Defense Game: Game Loop and Initializing PyGame

2022-03-29T12:42:14.870893+00:00

Tower Defense Game: Game Loop and Initializing PyGame

How do you instruct your computer game to draw things to the screen consistently and to a drum-beat that ensures there’s no awkward pauses or jitter? What about listening to the keyboard and mouse inputs, or updating the score board for your game?

Get any one of these things wrong, or forget to do them, and your game misbehaves. Worse, it can misbehave in ways that you won’t necessarily catch on your own machine.

That’s why all computer games – big or small – has one (or more!) game loops that ensure the game carries out its most essential tasks in a repeatable and stable manner.

It’s time to write our skeleton game loop that will serve us throughout the course of the development of our tower defense game.

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Tower Defense Game: Finite State Automata / State Machines

2022-03-29T12:42:14.887520+00:00

Tower Defense Game: Finite State Automata / State Machines

Complex codebases – and games are usually complex – tend to rely on a lot of state, usually captured in variables. Navigating from one screen in a game to another involves a lot of change: you need to render different things; the key bindings you use may change also; and perhaps you need to clear out old objects, like if you change from game play to the score screen.

But instead of having an ever-increasing number of variables to represent what your code is supposed to do – like, is_in_menu, has_won_game, is_in_level_editor, etc. – you should consider formalizing your stateful code using finite state automata, or commonly called a state machine.

To improve our code’s extensibility, it’s time to consider how we can effectively use a simple state machine to represent the state the game is in, and how OOP and inheritance can help with separation of concerns.

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Tower Defense Game: Basic Game Template

2022-03-29T12:42:14.900765+00:00

Tower Defense Game: Basic Game Template

It’s time to start handling events and drawing things to the screen. Building on the state machine and the controller layer from before, we need a simple abstraction to represent each of the screens we need. Luckily, there’s an easy way to do this with class inheritance and a bit of forward thinking.

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Tower Defense Game: Handling Sprites

2022-03-29T12:42:14.916761+00:00

Tower Defense Game: Handling Sprites

Sprites are entities – usually graphical – that you draw on the screen. We’ll need quite a lot of them in our Tower Defense Game: projectiles, enemies, the vegetation that makes up the game play area, and the text for the HUD.

To complicate matters, they all require their own unique set of features to make our game feel complete and professional: our projectiles fly through the air, so they need to move and rotate as they go. When they explode on impact, they need to fragment into pieces, so we need to think about animations and collision detection. Our enemies need move and death animations, and they should smoothly walk along a path from the spawn to the escape point.

It’s time we look at how to build sprites in PyGame.

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Tower Defense Game: Tile Engine & Map Editor

2022-03-29T12:42:14.943354+00:00

Tower Defense Game: Tile Engine & Map Editor

Our tower defense game needs a simple grid-like system for placing certain sprites, like the roads, as it makes it easier to build a path finding algorithm later on, so the enemies can find their way from start to finish.

Although grids are useful, we won’t limit ourselves to just that; shrubs, trees and other graphical ornaments don’t need a grid at all, so whatever we build, it should work with both.

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Tower Defense Game: Animation and Kinematics

2022-03-29T12:42:14.957625+00:00

Tower Defense Game: Animation and Kinematics

A tower defense game needs movement: the enemies should lumber across the battle field, and our turrets’ vision should sweep menacingly, looking for targets to fire its projectiles at.

Meanwhile, we need to think about path finding and animation, too. They’re all related, actually, because it’s about motion — kinematics.

All these things take place over seconds and minutes, which we must encapsulate into a system that works with our game loop and our desired frame rate. There’s many ways to do this, like for loops with accumulator variables to hold the state. But there’s another way to do it: with itertools, generators and lazy evaluation.

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Tower Defense Game: Path Finding

2022-03-29T12:42:14.982391+00:00

Tower Defense Game: Path Finding

Instead of making the level designer draw out the path for the enemies to walk, it makes sense to generate a path automatically using graph theory and a little bit of recursion. We want an algorithm that can generate all legal path combinations if there’s more than one entrance or exit, also.

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Tower Defense Game: Game Modes & Collision Detection

2022-03-29T12:42:14.997546+00:00

Tower Defense Game: Game Modes & Collision Detection

We’ve got path finding and movement for both the projectiles and the enemies. Now it’s time to think about collision detection. Our turrets need a way of detecting enemies in their sight range, and we want our flying projectiles to detect when they’ve struck an enemy.

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